Product roadmap · v0.1 · April 2026
earnd is a voice-first financial admin app for UK tradespeople — built by people who understand tax, designed for people who hate paperwork. This document is the complete build guide: concept, architecture, tasks, and developer briefs.
01 — Elevator pitch
For developers, investors, and partners
earnd is a mobile app that does the admin for tradespeople — automatically. A plumber finishes a job, speaks to their phone for 30 seconds, and earnd turns that into a professional invoice, logs their materials, tracks their mileage, and files it for their tax return — all without opening a spreadsheet. The government is forcing every self-employed person in the UK to submit tax data quarterly from 2026 onwards. Most tradespeople have no idea how to do this, and don't want to learn. earnd does it for them. It's built on top of an existing tax advisory firm, so the financial logic is baked in from day one — not bolted on later. Revenue comes from a monthly subscription, and the firm's existing client base of tradespeople is the launch audience.
Tradespeople hate admin. MTD (Making Tax Digital) is making it unavoidable. Existing tools are desktop-first, complex, and built for accountants — not plasterers.
Voice-first mobile app. Speak the job, earnd does the rest. Invoicing, expenses, mileage, MTD quarterly submissions — all handled automatically with zero spreadsheets.
Tax advisory firm backing. HMRC logic is baked in. MTD submissions go through the firm as registered agent — clients stay dependent, firm scales without proportionally more staff.
~2.1M
Self-employed tradespeople in the UK. All need MTD compliance from April 2026.
£180k
500 paying subscribers at £30/mo average. Achievable via existing firm client base + referral.
£15–£40
Core (£15), Pro with MTD (£25), Pro + Tax advisory (£40). Annual discount available.
02 — App overview & shape
Think of earnd as three layers sitting on top of each other. The user sees only the simple mobile app. Underneath that is a smart engine that organises their data. At the bottom, invisible to the user, is the HMRC bridge that handles compliance.
Three-layer architecture — user sees only the top layer; everything below runs automatically
Plain English: The app is a mobile front-end. Behind it, a Cloudflare Worker (a small server programme) handles the logic. The database sits inside Cloudflare too (called D1). HMRC has its own API (a connection point) that the app talks to directly. No complicated server to manage.
Speak after a job. AI converts speech to structured data: client name, job type, materials used, time spent, address for mileage.
Invoice generated automatically from voice log. Sent via PDF or direct link. Payment tracked. Reminders sent if unpaid after 14 days.
Photo a receipt or speak an expense. AI categorises it (materials, tools, fuel, PPE). Labour vs materials split calculated automatically.
GPS-based auto-log, or voice entry. 45p/mile claim calculated. Commute excluded. Home-to-first-job rules applied correctly.
Rolling 12-month threshold watch. Alerts at £75k, £80k, £85k. Flat rate vs standard comparison. Auto-flags adviser when needed.
Quarterly income + expenses compiled automatically. Submitted to HMRC via registered agent (the tax firm). No user action required.
03 — Data flows
Understanding data flow is key for any developer joining this project. There are three main flows: what the user puts in, how the system processes it, and how it gets to HMRC.
Flow 1 — speech becomes structured data, then an invoice, in under 5 seconds
Flow 2 — quarterly MTD submission handled entirely in the background
Flow 3 — a photograph becomes a tax-deductible expense entry in seconds
04 — Technical relationships
Every relationship in the app has specific data requirements. This section is primarily for developers — it defines exactly what data passes between each component.
For non-technical readers: Think of each relationship below as a pipe between two rooms. The "sends" column is what goes into the pipe; "receives" is what comes out. The "format" is the language the two sides speak to each other in (always JSON — a simple structured text format).
App sends →
Worker returns →
Key requirements
Worker sends →
AI returns →
Key requirements
Core tables
users — profile, tier, adviser_idjobs — date, client, amount, vat, typeexpenses — amount, category, vat, receipt_urlinvoices — job_id, status, sent_at, paid_atmileage — date, miles, purpose, from, tosubmissions — quarter, status, hmrc_refKey queries
Key requirements
We send →
HMRC returns →
Key requirements
| Table | Key fields | Relationships | Notes |
|---|---|---|---|
users |
id, email, utr, trade_type, tier, adviser_id, vat_registered | → jobs, expenses, invoices, submissions | UTR stored encrypted. Tier controls feature access. |
jobs |
id, user_id, client_id, date, labour_amount, materials_amount, vat_charged, description | → invoices, → mileage (via date) | Labour/materials split is critical for VAT reclaim calc. |
expenses |
id, user_id, date, amount, vat_amount, category, receipt_url, ai_confidence | → submissions (aggregated) | ai_confidence flags low-confidence categorisations for review. |
invoices |
id, job_id, user_id, pdf_url, sent_at, paid_at, amount, status | ← jobs | Status: draft / sent / viewed / paid / overdue |
mileage |
id, user_id, date, miles, from_postcode, to_postcode, purpose, rate_per_mile | → submissions (aggregated) | Rate switches from 45p to 25p after 10,000 miles/year. |
submissions |
id, user_id, quarter, period_start, period_end, income, expenses, hmrc_ref, status, submitted_at | ← users; → HMRC | Immutable once submitted. Amendments tracked separately. |
clients |
id, user_id, name, email, phone, address, vat_number | ← jobs, ← invoices | Auto-created from voice logging. User can enrich later. |
05 — Roadmap & tasks
Five phases. Each phase has a clear goal and a set of tasks. Tick them off as you go — progress is saved in your browser.
06 — Developer roles
You don't need everyone at once. Here's the order to hire, what each role does, what to brief them on, and realistic cost expectations for UK freelancers.
Backend / API developer
First hire — the most critical role. Builds the Cloudflare Worker, database, and all AI integrations.
They build
Brief them with
Mobile developer (React Native)
Builds the iOS and Android app. Can overlap with backend developer — start 4 weeks after backend begins.
They build
Brief them with
UX / UI designer
Designs every screen before any code is written. Tradespeople have low tolerance for complexity — UX must be exceptionally simple.
They deliver
Brief them with
Tax logic reviewer (internal — you)
This is your competitive advantage. You review every tax calculation the backend produces and sign off on correctness. Not a hire — this is your domain expertise contributing directly.
Your responsibility
What to document
Total estimated build cost (MVP): £60,000–£90,000 for all three external roles to MVP launch. This can be reduced significantly by using offshore developers for the backend (India/Eastern Europe) while keeping UX UK-based. Break-even at ~200 subscribers at £30/mo = ~6 months post-launch at modest growth.
Alternative route: Use a no-code / low-code agency to build a simpler v1 in 8–10 weeks for £15–25k (e.g. Bubble for web app, Adalo or Bravo for mobile). Launch this to validate demand, then rebuild properly with the budget above once you have 50+ paying customers. Faster and cheaper to prove the concept.